Destruction of the electrical conductivity of films



Patented Feb. 1, 1927.

UNITED STATES cnav'rou PATENT OFFICE.

T BIDLE ULBEY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR T WESTING- HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

DESTRUCTION. OF THE ELECTBICAE CONDUCTIRITY OI FILES.

Io Drawing.

This invention relates to evacuated elec trical devices and more particularly to methods of destroying the electrical conductivity of films between leading-in wires -or electrodes sealed therein.

An object of my invention is the provision of a method for salvaging evacuated electrical devices, for example, radio tubes, which have been shoi't-circuited by a deosit of conductive material on the press,

tween two or more leading-in wires thereof.

Another object of -my invention is the elimination of conductive films, which may r be deposited between the leading-in conductors of evacuated electrical devices,-thereby causin short circuits, by subjecting such films to e ectrical treatment to destroy their -,-electrical conductivity. .A further object of my invention is the destruction of short-circuiting films or deposits of clean-up or getter material,.which may have been formed on the press of a radio bulb or the like, by subjecting the same to .an electrical discharge. a a

A still further object of my invention is the treatment of evacuated electrical devices, for example, radio bulbs, which have been rendered inoperative because ofthe formation'of a conductive film of clean-up or etter material on the ress between the le ing-in wires -to the grid, plate and filament, to restore them to their operative condition by destroying the electrical conduc tivity of such film by an electrical discharge.

Other. objects and advantages of, the In vention will become apparent upon reading the following detaileddescription.

' For cleaning up residual gases in evacu ated electrical devices, for example, radio tubes, it has become ve common to use a metallic clean-up materia such as aluminum,

magnesium, calcium or the like. Such matonal may be fastened to or deposited on the plate of such a radio bulb an activated 'or vaporized by heating said plate to such temperature as to vaporize the clean-up material, in whole or in art, until the r uired de of vacuum is o tained in the b b.

. order to be sure ofoproperly eliminating residual and electr e-occluded gases, an excess of clean-up material is used in practice. If the clean-up material is vaporized to a greater extent than that which will combine with "such which is the usual portion of the bulb surface free for the therein by electrical means.

Application filed January 3, 1923. Serial No. 810,526.

case, a film or mirror of metallic material will be deposited on the inner wall of the bulb. It is desirable to so restrict such film or mirror as not to interfere with the proper observation of the filament when the-tube is in operation and not to cause short-circuiting between leading-in conductors.

It has been found, in practice, that such IIllI'IOI may be so restricted as to leave a proper observation of the interiorthereof, but it is not always possible to prevent some of the material from depositing on the press between leading-in conductors, thereby short-circuiting or providing a conductive path between said conductors and rendering the tube inoperative. Prior to my invention, radio bulbs, s'hort-circuited as aforedescribed, were considered worthless and, consequently, were scrapped. According to my invention, I have devised a con venient, simple and efiicient method of salvaging such tubes b destroying the electrical conductivity 0 short-circuiting films i My method of destroying the conductivit I of such films comprises connecting the lea ing-in wires of the device momentarily to a single wire or terminal of a source of high-potential and preferably high-freuency current. The same apparatus used or vaporizing the metallic clean-up agent, which formed the undesirable short-circuit- 1 ing film on the press of the radio bulb, may also be used for destroying the conductivity of such film. That is, the lead wires cf the device may be connected to one terminal of the source of high-frequency current which was used for vaporizing or activating the metallic clean-up agent employed. The 96 treatment is accomplishedin a few seconds without the use of any accessory apparatus. Although it is not definitely known how such treatment affects a metallic film to render' it non-conductive, it is thought that the 100 eflect is like a mechanical disintegration of the film and is not the resultof any purely heating action because of a current passed therethrough. The current passing through the film by such treatment is principally dueto the capacitance of-the device being treated and apparently too-small to cause any appreciable vaporization of the metallic material. The film on the press and interior of the bulb apparently serves as a plate of 10 appreciable. change in the appearance of the film Although I have attempted to explain the effect of the proposed treatment, I do not wish to be limited to the theory advanced in connection therewith, the main point being that, according to my invention, I may render non-conducting any metallic films deposited on the portion of an evacuated electrical device, through which leading-in conductors are sealed, in an eflicient, convenient and rapid manner by the "application of highirequency, high-potential current thereto, without efi'ecting any material change in the appearance of the film.

After treatment according to my inven- I tion, the device so salvaged may he used for the purpose for which it was normally in tended, just as if no short-circuiting film had been formed thereon.

Although I have described what I now consider the preferred embodiment of my invention, it is to be understood that'the 35 "same is merely illustrative and that myinvoltage thereon.

vention may be uwd for destroying the electrical conductivity of such undesirable conducting films between leading-in wires in any evacuated device, without departing from the spirit and scope of the appended claims.

What is claimed is:

1. The method of destroying the electrical conductivity of a film of metallic material comprising pressing intermittent high 2. The method of increasing the resistance of an electrically conductive film formed bev tween leadingin wires in an electrical device comprising impressing intermittent high-potential electricity thereon.

3. The method of salvaging evacuated electrical devices which have been rendered inoperative because of :a film of cleanup material deposited between leadingdn con-' ductors comprising connecting said leadingin conductors to one terminal of a source of intermittent high-potential .and. thereby destroying the electrical conductivity of said film and rendering the device suitable for normal use. 4

4. The method of destroying the conductivity of a film of metallic clean-up material in an evacuated electrical device compr' connecting said film to a source of high-fie.

quency, high-potential current.

In testimonywhereof, I have. hereunto subscribed my name this second day of Jannary, 1923.

CLAYTON TRIDLE ULREY.

(Ill 

